Self-propelled machines, such as lawnmowers and the like, often provide handles on which controls are mounted for manipulation by operators or users of such machines. In particular, a “walk behind” type self-propelled machine typically has a handle extending behind a power plant or other main operative assembly of the machine for gripping by the operator as the operator walks behind the machine during movement thereof in a forward direction. Typically, one or more controls are mounted towards the end of the handle in a convenient location for the user to manipulate while gripping the handle and operating the machine. Typically, any control device mounted to the handle is capable of implementing only a single function. Accordingly, the ability of an operator to control multiple types of functions has conventionally required the mounting of multiple types of control mechanisms or other devices on the handle of the machine. Unfortunately, recent marketing research indicates that many consumers of self-propelled machines would prefer a minimum number of control mechanisms requiring their manipulation during operation of such machines in order to simplify use of the machines.
Many examples exist of conventional self-propelled machines that require the use of multiple, separate controls to implement different functions. U.S. Patent Application Pub. No. U.S. 2002/0183145 to Blanchard discloses a variable-speed transmission for a self-propelled lawnmower. The transmission is coupled to a motor by means of a drive belt carried by a variable-pitch pulley rotating with the motor's shaft and a variable-pitch pulley rotating with the transmission's input shaft. A manual speed control cable actuates the transmission's variable-pitch pulley. To engage or disengage a clutch internal to the transmission, however, a separate control mechanism and associated cable are required. Accordingly, a lawnmower equipped with this transmission would require separate controls on its handle for manipulation by the operator in order to engage/disengage the clutch and adjust speed.
Some approaches have been taken in which a single transmission cable is employed to control a clutch, transmission speed, or both, but are considered to be excessively complex, costly, unreliable, or to otherwise leave room for improvement. For example, U.S. Pat. No. 6,062,083 to Dunegan discloses a variable-speed lawnmower a stationary handle attached to a mower deck and a large, plastic molded handle grip that slides up and down relative to the stationary handle. A pivot rod is disposed inside the handle grip, and slides along a channel formed within the handle grip. A transmission cable is secured to an assembly within the handle grip mechanically associated with the pivot rod. The handle grip can be slid down the stationary handle by an operator. The sliding motion of the handle grip is converted into pivoting motion of the pivot rod by means of the cam-like interface between the pivot rod and the channel, and results in the transmission cable being pulled upwardly to increase tension in a drive belt and thus increase speed. A second embodiment disclosed in U.S. Pat. No. 6,062,083 to Dunegan operates on the same principle, but substitutes a plurality of linkages for the pivot rod and the channel. Additional examples of the use of a single transmission cable are disclosed in U.S. Pat. No. 6,475,109 to Blanchard; U.S. Pat. No. 4,882,897 to Oshima et al.; and U.S. Pat. No. 4,835,949 to Severle; and U.S. Patent Application Pub. No. U.S. 2003/0056481 to Trefz.
Therefore, in self-propelled machines, and particularly those equipped with variable- or multi-speed transmissions, there continues to exist a need for providing improved apparatuses and methods for controlling both the coupling/decoupling and speed adjustment functions of the transmission using a single linking member manipulated by an operator of a machine.